There are various known devices for fixing the pedal to a support piece of the pedal. U.S. Pat. No. 4,819,500 describes a pedal that is fixed to a support piece that is attached to a motor vehicle. The pedal being fixed between two substantially parallel walls of the support piece by means of a shaft that passes through the pedal. The shaft is fixed to the support piece by means of a screwed connection, by a threaded bolt that passes longitudinally through the shaft.
For the purpose of obtaining an inexpensive and rapid fitting system that minimizes the assembly and detachment operations, Spanish Patent No. 2,273,244 T3 describes a shaft made of a plastic material, which is inserted axially in a support, passing through the support and the pedal. Once inserted it is rotated in relation to the support to a locking position. To achieve this, the shaft comprises a headstock that includes elastic clips that are locked with the support.
In French Publication No. 2796012A1 the shaft is made of a plastic material and fixed to a support by rapid coupling means. The rapid coupling means comprise projections on the outer wall of the support and stoppers on a head of the shaft, the stoppers respectively collaborating with the projections to fix and lock the shaft in relation to the support.
In the prior art there are known shafts of rotation made solely of plastic, in particular of polyamide or similar plastics, which are very rigid and resistant to cutting. One problem associated with hygroscopic plastics such as polyamide is the changes caused to their shape as a result of the temperature and/or moisture levels to which the materials are subjected. When they reach high temperatures and/or moisture levels shafts made of polyamide or similar plastics absorb moisture and become enlarged. As a result, the members that collaborate with the shafts are designed with lots of play, which negatively affects the accuracy of the rotary movement of the pedal in relation to the shaft and the effective transmission of stresses towards the support piece.